The goal of this set of analyses is to take a deeper dive into the 2019 Seattle calls for service data. To follow up on the preliminary exploratory analysis, we will focus on three types of cases - Disturbance, Suspicious person, and trespass - as well as one type of case resolution - No possible action possible. The questions we want to address here include the following:

  1. Where were each of the these types of cases commonly occurring?
  2. How were these three types of cases resolved?
  3. Does the type of resolution differ by location?
  4. What types of cases were cleared without police action?
  5. Where are the cases that were resolved without police action located?

Focal Case Types

To start, we will reducing the 2019 calls for service data to the three case types of interest. The frequencies of each type are shown below in Table 1. Disturbance cases total just under 100,000, suspicious person cases amount to under 50,000, and trespass cases were just under 25,000.

Table 1: Frequency of Focal Case Types
Case Type # of Calls
Disturbance 92,398
Suspicious Person 48,878
Trespass 24,500

Where are these 3 types of cases occurring?

Distribution of Cases across Seattle

Table 2 breaks down the density of calls per square mile in the city.

Table 2: Frequency and Density of Focal Case Types in Seattle
Case Type # of Calls Calls per Sq. Mile
Disturbance 92,398 615.22
Suspicious Person 48,878 325.45
Trespass 24,500 163.13

Precinct-Level Distribution

Even when we limit our focus to disturbance, trespass, and suspicious person cases, the north and west precincts lead in the number calls. Table 3 indicates that the north and west precincts together had just under 60% of all calls for the three types of cases. Further, the north had just about double the number of calls for these types of cases than the south precinct. Note: unknown is designated as the southernmost and northernmost boundaries of the city as well as the harbor areas.

Table 3: Calls By Precinct for all 3 Case Types
Precinct # Calls %
NORTH 48,881 30.55
WEST 44,808 28.01
EAST 25,574 15.98
SOUTH 23,839 14.90
SOUTHWEST 16,870 10.54
UNKNOWN 24 0.02

The bar graph below (Figure 1) breaks down the types of cases within each precinct. Below figure 1, Table 4 presents the frequencies, percentages, and densities for each case type and precinct.

Disturbances are the majority of cases in all precincts. Although over 50% of the focal cases are disturbance in all five precincts, the northern precinct had about 4 to 5 percentage point fewer disturbance cases than the other four precincts. This seems to be driven by the fact that the northern precinct had a sizable amount of suspicious person cases - 35.5%.

The north and southwest precincts lead in the share of suspicious persons. Just over one-third of the calls in these two precincts are about suspicious persons. In fact, in the southwest precinct, there were only 4,000 fewer calls about suspicious persons than disturbances.

The western precinct has the highest number and share of trespass calls. 22% of all calls in the western precinct were reports of trespassing. Notice that in the western precinct the trespass and suspicious person calls have very similar percentages. No other precincts had two case types that were equally distributed. Lastly, the number of calls about trespassing in the western precinct - 10,216 - doubled the number of calls in each of the other precincts.

In terms of density, the east and west precincts stand out as having the highest density of calls for all three types of cases. The density of disturbance and suspicious persons calls in the east precinct edges out the density of those cases in the west. However, with trespass cases, the west precinct’s density is higher than the east precinct.

Table 4: Distribution of Calls By Precinct & Case Type
Case Precinct # Calls % in Precinct Calls per Sq. Mi.
Disturbance SOUTH 13,873 58.19 759.06
Disturbance SOUTHWEST 9,699 57.49 494.31
Disturbance EAST 14,673 57.37 1,816.18
Disturbance WEST 25,312 56.49 1,807.54
Disturbance NORTH 25,778 52.74 740.00
Suspicious Person SOUTHWEST 6,072 35.99 309.46
Suspicious Person NORTH 17,286 35.36 496.23
Suspicious Person SOUTH 7,294 30.60 399.09
Suspicious Person EAST 6,616 25.87 818.91
Suspicious Person WEST 9,551 21.32 682.04
Trespass WEST 9,945 22.19 710.17
Trespass EAST 4,285 16.76 530.39
Trespass NORTH 5,817 11.90 166.99
Trespass SOUTH 2,672 11.21 146.20
Trespass SOUTHWEST 1,099 6.51 56.01

Sector Level Case Distribution

Interactive Map of Sector Density

The different layers show the sector density for the case types. Sectors in the core, particularly, M, K, and E have the highest densities.

Figures 2.1 through 2.3 show the number of cases in each sector. NOTE: Sector 99 - the northern and southern-most strips of land in the map - does not belong to a precinct.

Disturbances

  • In the western precinct, the high number of disturbance cases is driven by sectors K and D. These were some of the highest density sectors in the map above.
  • In the eastern precinct, disturbance cases are driven by sector E.
  • The southwestern precinct was the only precinct with cases relatively equally distributed across each of its sectors - W and F.

Suspicious Person

  • Sectors in the northern precinct - B and U - contain the most suspicious persons cases. Notice that in terms of density of suspicious persons cases, B and U do not stand out as having particularly high rates relative to the sectors in the west precinct.
  • The eastern precinct has sectors with the lowest amounts of cases - sectors M and U.

Trespass

  • The distribution of trespass cases seems to mirror that of disturbances.
  • K, M, and D sectors in the western precinct are among the top five sectors with trespass cases. * The eastern precinct also had large number of trespass cases, and the count is largely driven by sector E.
  • The southwestern precinct’s sectors had the fewest number of trespass cases (and the south to a lesser extent).

Beat-level distribution

Interactive Beat Density Map

Figures 3.1 through 3.3 show the number of cases in the three beats with the highest frequencies. Recall that beats are nested within sectors and sectors are nested within precincts. The letter in each of the beat names indicates the sector that the beat is located in. The color of the dot in the figures indicates the precinct the beat lies within. The 99 sector does not have beats, so it is excluded in the figures below.

Disturbances

  • West precinct beats K2 and K3 have the highest frequencies of disturbances. The K2 beat includes Pioneer Square, sporting complexes - T-Mobile Park and Lumen Field - and the Amtrak yard. Just to the east of K2 is K3, which encompasses the Chinatown/International District.
  • The northern precinct beats had high frequencies as well, particularly beat U2, which is where the University of Washington is located. In the map above, you will notice it also has a relatively high density compared to its neighboring beats.
  • The southwest precinct’s top 3 beats are noticeably lower than the rest of the beats, with the exception of beat W2, which is around the lower-middle of the distribution.

Suspicious Person

  • The top 3 beats are in the northern precinct. U2 - the beat encompassing the University of Seattle - is at the top, but beats N3 and B1 have similarly high frequencies.
  • The southern precinct beat R2 is also quite high. It stands out for its case count being noticeably higher than the 2nd and 3rd highest beats in the southern precinct.
  • Beats in the east, south, and southwestern precincts have similar frequencies.

Trespass

  • The top 3 beats are in the western precinct - K2, K3, and M3. K2 and K3 also had substantial disturbance cases. M3 is the smallest beat in the city. It encloses the Central Business District. M3 consistently has the highest density of cases across all case types.
  • Between the top 3 beats and the rest of the beats there is a appreciable drop-off in frequencies.
  • The top 3 east beats - E1, E2, and E3 - are the next highest. The frequencies for these three beats are about half that of the western beats. E1 and E2 split Capitol Hill. E3 appears to contain First Hill.

Resolutions by Case Type

Assistance rendered is the most common type of resolution for each of the three case types. Report written with no arrest is the next most common resolution for disturbance and trespass cases, and the third for suspicious person. Another common resolution was not being able to locate the incident/complainant, ranking third most common for disturbances, second in suspicious person cases, and fifth in trespass cases.

No police action deemed possible or necessary was fourth most common resolution for disturbance and suspicious persons cases. For trespass cases, no police action deemed possible or necessary was the sixth most common resolution with fewer than 1,000 cases.

There were some top-five resolutions that were unique to certain case types. For disturbances, responding units being canceled by the radio rounded out the top five types of resolutions. The ranking of resolutions for suspicious persons cases looked similar to disturbances. However, the suspicious persons top five was rounded out here with a written street check, though the total calls is noticeably lower than the no-police action necessary or possible resolution. The rankings for trespass cases differed from the other two types. For trespass cases, physical arrests and oral warnings were the third and fourth most common resolutions. Still, the number of trespass cases resolved with arrests and oral warnings are about one-quarter and one-tenth the number resolved by police rendering assistance.

Let’s focus on the top-5 resolutions for these cases of interest (as well as the (and no police action deemed necessary or possible for trespass, which falls just outside of the top 5). In the map series below we start to map these out.

Cases where no police action was possible or necessary

No police action was deemed possible or necessary for 19,290 calls. There are 63 types of cases that had been deemed impossible or unnecessary for police action to be taken. In the graph below, the number of calls for each of the top 20 case types with the no police action resolution are shown. You can see disturbance and suspicious person are the top 2 most common. Disturbance calls make up about 27% of these cases and suspicious person cases are 15%. Trespass cases are in the top 20, but rank lower than our other two focal cases at 9th most frequent.

Other Thoughts:

  • Suspicious circumstances - The frequencies seem to closely track with suspicious person cases. Perhaps run comparisons between suspicious persons and circumstances spatially.
  • Prowler - Trespass and prowler also tend to mirror each other in tabulations. Tracking these two spatially may be useful too.

The precinct-level map shows that the cases resolved without police action are largely in the north and west precincts.

Kernel Density

Interactive Map of Getis-Ord GI Hot Spots

The hot spots (and few cold spots) are a little harder to see in an interactive map. They are more localized because I used a 1/8th square mile pixel grid in build the raster. Pan and Zoom in to the different beats to see where the “hot spots” are located (e.g., near parks, transit stations, etc.)